The present invention relates to a method for manufacturing a color filter used for a color TV camera or the like.
There are basically two conventional methods for manufacturing the color filter of this type.
According to the first method, first to third color base films of predetermined patterns are formed on a glass substrate with a transparent resist film interposed between each pair of adjacent base films so that the first to third color base films do not overlap with each other. The first color base film is directly formed on the glass substrate. The second color base film is formed on a first resist film and the third color base film is formed on a second resist film. The first to third color base films are formed under different conditions, resulting in a difference in adhesion and peel-off of the base films. Further, steps are formed between the color base films. Therefore, printing resolution in the second color and then in the third color is degraded, resulting in blurs of the patterns.
According to the second method, a stripe-shaped light-shield metal film is formed on a glass substrate. Thereafter, a base film to be dyed is formed to cover the entire surface. A first photoresist film is then formed on the base film. First windows are formed at predetermined positions defined by the light-shield metal film. The base film is selectively dyed with a first color (e.g., red) through the first windows. Similarly, second windows are formed at predetermined positions adjacent to the first windows, using a second photoresist film as a mask. The base film is selectively dyed with a second color (e.g., green) through the second windows. Further, third windows which do not overlap the first and second windows are formed using a third photoresist film as a mask. The base film is then selectively dyed with a third color (e.g., blue) through the third windows.
However, since the base film which is formed on the light-shield metal film is horizontally continuously dyed with different colors, each color tends to spread horizontally and the different colors may be mixed at their boundaries, resulting in degradation of optical characteristics.
In order to prevent spreading of colors, grooves are formed to divide the color base film on the light-shield metal film into layers of different colors. The groove patterns are printed and developed using the photoresist films as masks. However, if the width of the light-shield metal film is as small as 2 to 3 .mu.m, the base film to be dyed may be etched due to imprecise masking and alignment errors, thus decreasing the yield of the color filters. The color base film is exposed by warped light beams and pattern edges thereof are rounded. The color at the rounded portions becomes light and the distinct boundaries of the color layers cannot be obtained.
Cl SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for manufacturing a color filter wherein color pattern layers are formed on the same plane and do not have steps among the colored pattern layers, and adjacent colored pattern layers are separated from each other properly so as to prevent spreading of the color pattern layers, thus preventing color mixing.
According to a method for manufacturing a color filter of the present invention, a stripe- or lattice-shaped light-shield pattern is formed on one major surface of a transparent glass substrate. A photosensitive base film is formed to cover the entire surface of the glass substrate through the light-shield pattern. Light is then radiated on the other major surface of the glass substrate, using the light-shield pattern as a mask. Thus, the base film is exposed and nonexposed portions of the base film which are immediately above the mask are etched. Simultaneously, highly elaborate grooves are formed properly to isolate the adjacent colored pattern layers from each other.
As a result, a mask for isolating the adjacent colored pattern layers from each other need not be prepared separately. The alignment error does not substantially occur. The pattern edges may not be rounded. Therefore, a color filter has distinct boundaries of the colored pattern layers to provide large effective areas.